//==========================================================================
// Copyright (c) 2000-2008,  Elastos, Inc.  All Rights Reserved.
//==========================================================================
/*
 * Copyright (c) 1982, 1986, 1988, 1991, 1993
 *  The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *  This product includes software developed by the University of
 *  California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *  @(#)uipc_mbuf.c 8.2 (Berkeley) 1/4/94
 */

//#include <sys/netmisc.h>
//#include <sys/cdefs.h>
//__FBSDID("$FreeBSD: src/sys/kern/uipc_mbuf.c,v 1.120 2003/09/01 05:55:37 silby Exp $");

//#include "opt_mac.h"
//#include "opt_param.h"
//#include "opt_mbuf_stress_test.h"

//#include <sys/param.h>
//#include <sys/systm.h>
//#include <sys/kernel.h>
//#include <sys/lock.h>
//#include <sys/mac.h>
//#include <sys/malloc.h>
//#include <sys/mbuf.h>
//#include <sys/sysctl.h>
//#include <sys/domain.h>
//#include <sys/protosw.h>

#include "mbuf_.h"


int max_linkhdr;
int max_protohdr;
int max_hdr;
int max_datalen;
#ifdef MBUF_STRESS_TEST
int m_defragpackets;
int m_defragbytes;
int m_defraguseless;
int m_defragfailure;
int m_defragrandomfailures;
#endif

/*
 * sysctl(8) exported objects
 */
//SYSCTL_DECL(_kern_ipc);
//SYSCTL_INT(_kern_ipc, KIPC_MAX_LINKHDR, max_linkhdr, CTLFLAG_RW,
//     &max_linkhdr, 0, "");
//SYSCTL_INT(_kern_ipc, KIPC_MAX_PROTOHDR, max_protohdr, CTLFLAG_RW,
//     &max_protohdr, 0, "");
//SYSCTL_INT(_kern_ipc, KIPC_MAX_HDR, max_hdr, CTLFLAG_RW, &max_hdr, 0, "");
//SYSCTL_INT(_kern_ipc, KIPC_MAX_DATALEN, max_datalen, CTLFLAG_RW,
//     &max_datalen, 0, "");
//#ifdef MBUF_STRESS_TEST
//SYSCTL_INT(_kern_ipc, OID_AUTO, m_defragpackets, CTLFLAG_RD,
//     &m_defragpackets, 0, "");
//SYSCTL_INT(_kern_ipc, OID_AUTO, m_defragbytes, CTLFLAG_RD,
//     &m_defragbytes, 0, "");
//SYSCTL_INT(_kern_ipc, OID_AUTO, m_defraguseless, CTLFLAG_RD,
//     &m_defraguseless, 0, "");
//SYSCTL_INT(_kern_ipc, OID_AUTO, m_defragfailure, CTLFLAG_RD,
//     &m_defragfailure, 0, "");
//SYSCTL_INT(_kern_ipc, OID_AUTO, m_defragrandomfailures, CTLFLAG_RW,
//     &m_defragrandomfailures, 0, "");
//#endif



/*
 * "Move" mbuf pkthdr from "from" to "to".
 * "from" must have M_PKTHDR set, and "to" must be empty.
 */
void
m_move_pkthdr(struct mbuf *to, struct mbuf *from)
{

#if 0
    /* see below for why these are not enabled */
    M_ASSERTPKTHDR(to);
    /* Note: with MAC, this may not be a good assertion. */
    KASSERT(SLIST_EMPTY(&to->m_pkthdr.tags),
        ("m_move_pkthdr: to has tags"));
#endif
    KASSERT((to->m_flags & M_EXT) == 0, ("m_move_pkthdr: to has cluster"));
#ifdef MAC
    /*
     * XXXMAC: It could be this should also occur for non-MAC?
     */
    if (to->m_flags & M_PKTHDR)
        m_tag_delete_chain(to, NULL);
#endif
    to->m_flags = from->m_flags & M_COPYFLAGS;
    to->m_data = to->m_pktdat;
    to->m_pkthdr = from->m_pkthdr;      /* especially tags */
    SLIST_INIT(&from->m_pkthdr.tags);   /* purge tags from src */
    from->m_flags &= ~M_PKTHDR;
}

/*
 * Duplicate "from"'s mbuf pkthdr in "to".
 * "from" must have M_PKTHDR set, and "to" must be empty.
 * In particular, this does a deep copy of the packet tags.
 */

int
m_dup_pkthdr(struct mbuf *to, struct mbuf *from, int how)
{

#if 0
    /*
     * The mbuf allocator only initializes the pkthdr
     * when the mbuf is allocated with MGETHDR. Many users
     * (e.g. m_copy*, m_prepend) use MGET and then
     * smash the pkthdr as needed causing these
     * assertions to trip.  For now just disable them.
     */
    M_ASSERTPKTHDR(to);
    /* Note: with MAC, this may not be a good assertion. */
    KASSERT(SLIST_EMPTY(&to->m_pkthdr.tags), ("m_dup_pkthdr: to has tags"));
#endif
#ifdef MAC
    if (to->m_flags & M_PKTHDR)
        m_tag_delete_chain(to, NULL);
#endif
    to->m_flags = (from->m_flags & M_COPYFLAGS) | (to->m_flags & M_EXT);
    if ((to->m_flags & M_EXT) == 0)
        to->m_data = to->m_pktdat;
    to->m_pkthdr = from->m_pkthdr;
    SLIST_INIT(&to->m_pkthdr.tags);
    return (m_tag_copy_chain(to, from, MBTOM(how)));
}

/*
 * Lesser-used path for M_PREPEND:
 * allocate new mbuf to prepend to chain,
 * copy junk along.
 */
struct mbuf *
m_prepend(struct mbuf *m, int len, int how)
{
    struct mbuf *mn;

    if (m->m_flags & M_PKTHDR)
        MGETHDR(mn, how, m->m_type);
    else
        MGET(mn, how, m->m_type);
    if (mn == NULL) {
        m_freem(m);
        return (NULL);
    }
    if (m->m_flags & M_PKTHDR)
        M_MOVE_PKTHDR(mn, m);
    mn->m_next = m;
    m = mn;
    if (len < MHLEN)
        MH_ALIGN(m, len);
    m->m_len = len;
    return (m);
}

/*
 * Make a copy of an mbuf chain starting "off0" bytes from the beginning,
 * continuing for "len" bytes.  If len is M_COPYALL, copy to end of mbuf.
 * The wait parameter is a choice of M_TRYWAIT/M_DONTWAIT from caller.
 * Note that the copy is read-only, because clusters are not copied,
 * only their reference counts are incremented.
 */
 


struct mbuf *
m_copym(struct mbuf *m, int off0, int len, int wait)
{
    struct mbuf *n, **np;
    int off = off0;
    struct mbuf *top;
    int copyhdr = 0;

    KASSERT(off >= 0, ("m_copym, negative off %d", off));
    KASSERT(len >= 0, ("m_copym, negative len %d", len));
    if (off == 0 && m->m_flags & M_PKTHDR)
        copyhdr = 1;
    while (off > 0) {
        KASSERT(m != NULL, ("m_copym, offset > size of mbuf chain"));
        if (off < m->m_len)
            break;
        off -= m->m_len;
        m = m->m_next;
    }
    np = &top;
    top = 0;
    while (len > 0) {
        if (m == NULL) {
            KASSERT(len == M_COPYALL,
                ("m_copym, length > size of mbuf chain"));
            break;
        }
        if (copyhdr)
            MGETHDR(n, wait, m->m_type);
        else
            MGET(n, wait, m->m_type);
        *np = n;
        if (n == NULL)
            goto nospace;
        if (copyhdr) {
            if (!m_dup_pkthdr(n, m, wait))
                goto nospace;
            if (len == M_COPYALL)
                n->m_pkthdr.len -= off0;
            else
                n->m_pkthdr.len = len;
            copyhdr = 0;
        }
        n->m_len = min(len, m->m_len - off);
        if (m->m_flags & M_EXT) {
            n->m_data = m->m_data + off;
            n->m_ext = m->m_ext;
            n->m_flags |= M_EXT;
            MEXT_ADD_REF(m);
        } else
            bcopy(mtod(m, caddr_t)+off, mtod(n, caddr_t),
                (u_int)n->m_len);
        if (len != M_COPYALL)
            len -= n->m_len;
        off = 0;
        m = m->m_next;
        np = &n->m_next;
    }
    if (top == NULL)
        mbstat.m_mcfail++;  /* XXX: No consistency. */

    return (top);
nospace:
    m_freem(top);
    mbstat.m_mcfail++;  /* XXX: No consistency. */
    return (NULL);
}

/*
 * Copy an entire packet, including header (which must be present).
 * An optimization of the common case `m_copym(m, 0, M_COPYALL, how)'.
 * Note that the copy is read-only, because clusters are not copied,
 * only their reference counts are incremented.
 * Preserve alignment of the first mbuf so if the creator has left
 * some room at the beginning (e.g. for inserting protocol headers)
 * the copies still have the room available.
 */
struct mbuf *
m_copypacket(struct mbuf *m, int how)
{
    struct mbuf *top, *n, *o;

    MGET(n, how, m->m_type);
    top = n;
    if (n == NULL)
        goto nospace;

    if (!m_dup_pkthdr(n, m, how))
        goto nospace;
    n->m_len = m->m_len;
    if (m->m_flags & M_EXT) {
        n->m_data = m->m_data;
        n->m_ext = m->m_ext;
        n->m_flags |= M_EXT;
        MEXT_ADD_REF(m);
    } else {
        n->m_data = n->m_pktdat + ((char*)m->m_data - m->m_pktdat);
        bcopy(mtod(m, char *), mtod(n, char *), n->m_len);
    }

    m = m->m_next;
    while (m) {
        MGET(o, how, m->m_type);
        if (o == NULL)
            goto nospace;

        n->m_next = o;
        n = n->m_next;

        n->m_len = m->m_len;
        if (m->m_flags & M_EXT) {
            n->m_data = m->m_data;
            n->m_ext = m->m_ext;
            n->m_flags |= M_EXT;
            MEXT_ADD_REF(m);
        } else {
            bcopy(mtod(m, char *), mtod(n, char *), n->m_len);
        }

        m = m->m_next;
    }
    return top;
nospace:
    m_freem(top);
    mbstat.m_mcfail++;  /* XXX: No consistency. */
    return (NULL);
}

/*
 * Copy data from an mbuf chain starting "off" bytes from the beginning,
 * continuing for "len" bytes, into the indicated buffer.
 */
void
m_copydata(const struct mbuf *m, int off, int len, caddr_t cp)
{
    u_int count;

    KASSERT(off >= 0, ("m_copydata, negative off %d", off));
    KASSERT(len >= 0, ("m_copydata, negative len %d", len));
    while (off > 0) {
        KASSERT(m != NULL, ("m_copydata, offset > size of mbuf chain"));
        if (off < m->m_len)
            break;
        off -= m->m_len;
        m = m->m_next;
    }
    while (len > 0) {
        KASSERT(m != NULL, ("m_copydata, length > size of mbuf chain"));
        count = min(m->m_len - off, len);
        bcopy(mtod(m, caddr_t) + off, cp, count);
        len -= count;
        cp += count;
        off = 0;
        m = m->m_next;
    }
}

/*
 * Copy a packet header mbuf chain into a completely new chain, including
 * copying any mbuf clusters.  Use this instead of m_copypacket() when
 * you need a writable copy of an mbuf chain.
 */
struct mbuf *
m_dup(struct mbuf *m, int how)
{
    struct mbuf **p, *top = NULL;
    int remain, moff, nsize;

    /* Sanity check */
    if (m == NULL)
        return (NULL);
    M_ASSERTPKTHDR(m);

    /* While there's more data, get a new mbuf, tack it on, and fill it */
    remain = m->m_pkthdr.len;
    moff = 0;
    p = &top;
    while (remain > 0 || top == NULL) { /* allow m->m_pkthdr.len == 0 */
        struct mbuf *n;

        /* Get the next new mbuf */
        MGET(n, how, m->m_type);
        if (n == NULL)
            goto nospace;
        if (top == NULL) {      /* first one, must be PKTHDR */
            if (!m_dup_pkthdr(n, m, how))
                goto nospace;
            nsize = MHLEN;
        } else              /* not the first one */
            nsize = MLEN;
        if (remain >= MINCLSIZE) {
            MCLGET(n, how);
            if ((n->m_flags & M_EXT) == 0) {
                (void)m_free(n);
                goto nospace;
            }
            nsize = MCLBYTES;
        }
        n->m_len = 0;

        /* Link it into the new chain */
        *p = n;
        p = &n->m_next;

        /* Copy data from original mbuf(s) into new mbuf */
        while (n->m_len < nsize && m != NULL) {
            int chunk = min(nsize - n->m_len, m->m_len - moff);

            bcopy(m->m_data + moff, n->m_data + n->m_len, chunk);
            moff += chunk;
            n->m_len += chunk;
            remain -= chunk;
            if (moff == m->m_len) {
                m = m->m_next;
                moff = 0;
            }
        }

        /* Check correct total mbuf length */
        KASSERT((remain > 0 && m != NULL) || (remain == 0 && m == NULL),
                ("bogus m_pkthdr.len"));
    }
    return (top);

nospace:
    m_freem(top);
    mbstat.m_mcfail++;  /* XXX: No consistency. */
    return (NULL);
}

/*
 * Concatenate mbuf chain n to m.
 * Both chains must be of the same type (e.g. MT_DATA).
 * Any m_pkthdr is not updated.
 */
void
m_cat(struct mbuf *m, struct mbuf *n)
{
    while (m->m_next)
        m = m->m_next;
    while (n) {
        if (m->m_flags & M_EXT ||
            (char*)m->m_data + m->m_len + n->m_len >= &m->m_dat[MLEN]) {
            /* just join the two chains */
            m->m_next = n;
            return;
        }
        /* splat the data from one into the other */
        bcopy(mtod(n, caddr_t), mtod(m, caddr_t) + m->m_len,
            (u_int)n->m_len);
        m->m_len += n->m_len;
        n = m_free(n);
    }
}

void
m_adj(struct mbuf *mp, int req_len)
{
    int len = req_len;
    struct mbuf *m;
    int count;

    if ((m = mp) == NULL)
        return;
    if (len >= 0) {
        /*
         * Trim from head.
         */
        while (m != NULL && len > 0) {
            if (m->m_len <= len) {
                len -= m->m_len;
                m->m_len = 0;
                m = m->m_next;
            } else {
                m->m_len -= len;
                m->m_data += len;
                len = 0;
            }
        }
        m = mp;
        if (mp->m_flags & M_PKTHDR)
            m->m_pkthdr.len -= (req_len - len);
    } else {
        /*
         * Trim from tail.  Scan the mbuf chain,
         * calculating its length and finding the last mbuf.
         * If the adjustment only affects this mbuf, then just
         * adjust and return.  Otherwise, rescan and truncate
         * after the remaining size.
         */
        len = -len;
        count = 0;
        for (;;) {
            count += m->m_len;
            if (m->m_next == (struct mbuf *)0)
                break;
            m = m->m_next;
        }
        if (m->m_len >= len) {
            m->m_len -= len;
            if (mp->m_flags & M_PKTHDR)
                mp->m_pkthdr.len -= len;
            return;
        }
        count -= len;
        if (count < 0)
            count = 0;
        /*
         * Correct length for chain is "count".
         * Find the mbuf with last data, adjust its length,
         * and toss data from remaining mbufs on chain.
         */
        m = mp;
        if (m->m_flags & M_PKTHDR)
            m->m_pkthdr.len = count;
        for (; m; m = m->m_next) {
            if (m->m_len >= count) {
                m->m_len = count;
                break;
            }
            count -= m->m_len;
        }
        while (m->m_next)
            (m = m->m_next) ->m_len = 0;
    }
}

/*
 * Rearange an mbuf chain so that len bytes are contiguous
 * and in the data area of an mbuf (so that mtod and dtom
 * will work for a structure of size len).  Returns the resulting
 * mbuf chain on success, frees it and returns null on failure.
 * If there is room, it will add up to max_protohdr-len extra bytes to the
 * contiguous region in an attempt to avoid being called next time.
 */
struct mbuf *
m_pullup(struct mbuf *n, int len)
{
    struct mbuf *m;
    int count;
    int space;

    /*
     * If first mbuf has no cluster, and has room for len bytes
     * without shifting current data, pullup into it,
     * otherwise allocate a new mbuf to prepend to the chain.
     */
    if ((n->m_flags & M_EXT) == 0 &&
        (char *)n->m_data + len < &n->m_dat[MLEN] && n->m_next) {
        if (n->m_len >= len)
            return (n);
        m = n;
        n = n->m_next;
        len -= m->m_len;
    } else {
        if (len > MHLEN)
            goto bad;
        MGET(m, M_DONTWAIT, n->m_type);
        if (m == NULL)
            goto bad;
        m->m_len = 0;
        if (n->m_flags & M_PKTHDR)
            M_MOVE_PKTHDR(m, n);
    }
    space = &m->m_dat[MLEN] - ((char*)m->m_data + m->m_len);
    do {
        count = min(min(max(len, max_protohdr), space), n->m_len);
        bcopy(mtod(n, caddr_t), mtod(m, caddr_t) + m->m_len,
          (u_int)count);
        len -= count;
        m->m_len += count;
        n->m_len -= count;
        space -= count;
        if (n->m_len)
            n->m_data += count;
        else
            n = m_free(n);
    } while (len > 0 && n);
    if (len > 0) {
        (void) m_free(m);
        goto bad;
    }
    m->m_next = n;
    return (m);
bad:
    m_freem(n);
    mbstat.m_mpfail++;  /* XXX: No consistency. */
    return (NULL);
}

/*
 * Partition an mbuf chain in two pieces, returning the tail --
 * all but the first len0 bytes.  In case of failure, it returns NULL and
 * attempts to restore the chain to its original state.
 *
 * Note that the resulting mbufs might be read-only, because the new
 * mbuf can end up sharing an mbuf cluster with the original mbuf if
 * the "breaking point" happens to lie within a cluster mbuf. Use the
 * M_WRITABLE() macro to check for this case.
 */
struct mbuf *
m_split(struct mbuf *m0, int len0, int wait)
{
    struct mbuf *m, *n;
    u_int len = len0, remain;

    for (m = m0; m && len > m->m_len; m = m->m_next)
        len -= m->m_len;
    if (m == NULL)
        return (NULL);
    remain = m->m_len - len;
    if (m0->m_flags & M_PKTHDR) {
        MGETHDR(n, wait, m0->m_type);
        if (n == NULL)
            return (NULL);
        n->m_pkthdr.rcvif = m0->m_pkthdr.rcvif;
        n->m_pkthdr.len = m0->m_pkthdr.len - len0;
        m0->m_pkthdr.len = len0;
        if (m->m_flags & M_EXT)
            goto extpacket;
        if (remain > MHLEN) {
            /* m can't be the lead packet */
            MH_ALIGN(n, 0);
            n->m_next = m_split(m, len, wait);
            if (n->m_next == NULL) {
                (void) m_free(n);
                return (NULL);
            } else {
                n->m_len = 0;
                return (n);
            }
        } else
            MH_ALIGN(n, remain);
    } else if (remain == 0) {
        n = m->m_next;
        m->m_next = NULL;
        return (n);
    } else {
        MGET(n, wait, m->m_type);
        if (n == NULL)
            return (NULL);
        M_ALIGN(n, remain);
    }
extpacket:
    if (m->m_flags & M_EXT) {
        n->m_flags |= M_EXT;
        n->m_ext = m->m_ext;
        MEXT_ADD_REF(m);
        n->m_data = m->m_data + len;
    } else {
        bcopy(mtod(m, caddr_t) + len, mtod(n, caddr_t), remain);
    }
    n->m_len = remain;
    m->m_len = len;
    n->m_next = m->m_next;
    m->m_next = NULL;
    return (n);
}
/*
 * Routine to copy from device local memory into mbufs.
 * Note that `off' argument is offset into first mbuf of target chain from
 * which to begin copying the data to.
 */
struct mbuf *
m_devget(char *buf, int totlen, int off, struct ifnet *ifp,
     void (*copy)(char *from, caddr_t to, u_int len))
{
    struct mbuf *m;
    struct mbuf *top = 0, **mp = &top;
    int len;

    if (off < 0 || off > MHLEN)
        return (NULL);

    MGETHDR(m, M_DONTWAIT, MT_DATA);
    if (m == NULL)
        return (NULL);
    m->m_pkthdr.rcvif = ifp;
    m->m_pkthdr.len = totlen;
    len = MHLEN;

    while (totlen > 0) {
        if (top) {
            MGET(m, M_DONTWAIT, MT_DATA);
            if (m == NULL) {
                m_freem(top);
                return (NULL);
            }
            len = MLEN;
        }
        if (totlen + off >= MINCLSIZE) {
            MCLGET(m, M_DONTWAIT);
            if (m->m_flags & M_EXT)
                len = MCLBYTES;
        } else {
            /*
             * Place initial small packet/header at end of mbuf.
             */
            if (top == NULL && totlen + off + max_linkhdr <= len) {
                m->m_data += max_linkhdr;
                len -= max_linkhdr;
            }
        }
        if (off) {
            m->m_data += off;
            len -= off;
            off = 0;
        }
        m->m_len = len = min(totlen, len);
        if (copy)
            copy(buf, mtod(m, caddr_t), (u_int)len);
        else
            bcopy(buf, mtod(m, caddr_t), (u_int)len);
        buf += len;
        *mp = m;
        mp = &m->m_next;
        totlen -= len;
    }
    return (top);
}

/*
 * Copy data from a buffer back into the indicated mbuf chain,
 * starting "off" bytes from the beginning, extending the mbuf
 * chain if necessary.
 */
void
m_copyback(struct mbuf *m0, int off, int len, caddr_t cp)
{
    int mlen;
    struct mbuf *m = m0, *n;
    int totlen = 0;

    if (m0 == NULL)
        return;
    while (off > (mlen = m->m_len)) {
        off -= mlen;
        totlen += mlen;
        if (m->m_next == NULL) {
            n = m_get_clrd(M_DONTWAIT, m->m_type);
            if (n == NULL)
                goto out;
            n->m_len = min(MLEN, len + off);
            m->m_next = n;
        }
        m = m->m_next;
    }
    while (len > 0) {
        mlen = min (m->m_len - off, len);
        bcopy(cp, off + mtod(m, caddr_t), (u_int)mlen);
        cp += mlen;
        len -= mlen;
        mlen += off;
        off = 0;
        totlen += mlen;
        if (len == 0)
            break;
        if (m->m_next == NULL) {
            n = m_get(M_DONTWAIT, m->m_type);
            if (n == NULL)
                break;
            n->m_len = min(MLEN, len);
            m->m_next = n;
        }
        m = m->m_next;
    }
out:    if (((m = m0)->m_flags & M_PKTHDR) && (m->m_pkthdr.len < totlen))
        m->m_pkthdr.len = totlen;
}

void
m_print(const struct mbuf *m)
{
    int len;
    const struct mbuf *m2;

    len = m->m_pkthdr.len;
    m2 = m;
    while (len) {
        kprintf("%p %*D\n", m2, m2->m_len, (u_char *)m2->m_data, "-");
        len -= m2->m_len;
        m2 = m2->m_next;
    }
    return;
}

u_int
m_fixhdr(struct mbuf *m0)
{
    u_int len;

    len = m_length(m0, NULL);
    m0->m_pkthdr.len = len;
    return (len);
}

u_int
m_length(struct mbuf *m0, struct mbuf **last)
{
    struct mbuf *m;
    u_int len;

    len = 0;
    for (m = m0; m != NULL; m = m->m_next) {
        len += m->m_len;
        if (m->m_next == NULL)
            break;
    }
    if (last != NULL)
        *last = m;
    return (len);
}

/*
 * Defragment a mbuf chain, returning the shortest possible
 * chain of mbufs and clusters.  If allocation fails and
 * this cannot be completed, NULL will be returned, but
 * the passed in chain will be unchanged.  Upon success,
 * the original chain will be freed, and the new chain
 * will be returned.
 *
 * If a non-packet header is passed in, the original
 * mbuf (chain?) will be returned unharmed.
 */
struct mbuf *
m_defrag(struct mbuf *m0, int how)
{
    struct mbuf *m_new = NULL, *m_final = NULL;
    int     progress = 0, length;

    if (!(m0->m_flags & M_PKTHDR))
        return (m0);

    m_fixhdr(m0); /* Needed sanity check */

#ifdef MBUF_STRESS_TEST
    if (m_defragrandomfailures) {
        int temp = arc4random() & 0xff;
        if (temp == 0xba)
            goto nospace;
    }
#endif

    if (m0->m_pkthdr.len > MHLEN)
        m_final = m_getcl(how, MT_DATA, M_PKTHDR);
    else
        m_final = m_gethdr(how, MT_DATA);

    if (m_final == NULL)
        goto nospace;

    if (m_dup_pkthdr(m_final, m0, how) == 0)
        goto nospace;

    m_new = m_final;

    while (progress < m0->m_pkthdr.len) {
        length = m0->m_pkthdr.len - progress;
        if (length > MCLBYTES)
            length = MCLBYTES;

        if (m_new == NULL) {
            if (length > MLEN)
                m_new = m_getcl(how, MT_DATA, 0);
            else
                m_new = m_get(how, MT_DATA);
            if (m_new == NULL)
                goto nospace;
        }

        m_copydata(m0, progress, length, mtod(m_new, caddr_t));
        progress += length;
        m_new->m_len = length;
        if (m_new != m_final)
            m_cat(m_final, m_new);
        m_new = NULL;
    }
#ifdef MBUF_STRESS_TEST
    if (m0->m_next == NULL)
        m_defraguseless++;
#endif
    m_freem(m0);
    m0 = m_final;
#ifdef MBUF_STRESS_TEST
    m_defragpackets++;
    m_defragbytes += m0->m_pkthdr.len;
#endif
    return (m0);
nospace:
#ifdef MBUF_STRESS_TEST
    m_defragfailure++;
#endif
    if (m_new)
        m_free(m_new);
    if (m_final)
        m_freem(m_final);
    return (NULL);
}

#ifdef MBUF_STRESS_TEST

/*
 * Fragment an mbuf chain.  There's no reason you'd ever want to do
 * this in normal usage, but it's great for stress testing various
 * mbuf consumers.
 *
 * If fragmentation is not possible, the original chain will be
 * returned.
 *
 * Possible length values:
 * 0     no fragmentation will occur
 * > 0  each fragment will be of the specified length
 * -1   each fragment will be the same random value in length
 * -2   each fragment's length will be entirely random
 * (Random values range from 1 to 256)
 */
struct mbuf *
m_fragment(struct mbuf *m0, int how, int length)
{
    struct mbuf *m_new = NULL, *m_final = NULL;
    int     progress = 0;

    if (!(m0->m_flags & M_PKTHDR))
        return (m0);

    if ((length == 0) || (length < -2))
        return (m0);

    m_fixhdr(m0); /* Needed sanity check */

    m_final = m_getcl(how, MT_DATA, M_PKTHDR);

    if (m_final == NULL)
        goto nospace;

    if (m_dup_pkthdr(m_final, m0, how) == NULL)
        goto nospace;

    m_new = m_final;

    if (length == -1)
        length = 1 + (arc4random() & 255);

    while (progress < m0->m_pkthdr.len) {
        int fraglen;

        if (length > 0)
            fraglen = length;
        else
            fraglen = 1 + (arc4random() & 255);
        if (fraglen > m0->m_pkthdr.len - progress)
            fraglen = m0->m_pkthdr.len - progress;

        if (fraglen > MCLBYTES)
            fraglen = MCLBYTES;

        if (m_new == NULL) {
            m_new = m_getcl(how, MT_DATA, 0);
            if (m_new == NULL)
                goto nospace;
        }

        m_copydata(m0, progress, fraglen, mtod(m_new, caddr_t));
        progress += fraglen;
        m_new->m_len = fraglen;
        if (m_new != m_final)
            m_cat(m_final, m_new);
        m_new = NULL;
    }
    m_freem(m0);
    m0 = m_final;
    return (m0);
nospace:
    if (m_new)
        m_free(m_new);
    if (m_final)
        m_freem(m_final);
    /* Return the original chain on failure */
    return (m0);
}

#endif
